What does it mean to get 'leave' to apply for judicial review at Federal Court?

"Leave" is the Federal Court's permission to actually have a judicial review heard on its merits. Most immigration and refugee decisions carry no automatic right to a full hearing — instead, the applicant must first file a leave application, and a judge decides, based only on the written materials submitted, whether there is a fairly arguable case that the original decision was legally or procedurally flawed.

This first stage is a real screening step, not a formality. If leave is refused, that decision is final: there is no appeal from a refusal of leave, and the matter ends there unless some other avenue, such as a fresh application or a different type of request, is available. Only if leave is granted does the case move forward to a full hearing where the judicial review itself is argued and decided.

Because the leave stage is decided entirely on paper, without an oral hearing on the merits, the quality and clarity of the written materials submitted at this stage often matters as much as the strength of the underlying legal argument itself.